Compatibility Between Brain-Computer Interface and High Efficiency Augmentative and Alternative Communication Systems ABSTRACT Brain-computer interfaces (BCI) can now enable text production for people who cannot move, yet they provide only the simplest communication interfaces and have not been widely adopted. Current augmentative and alternative communication (AAC) systems are widely adopted and provide efficient production of precise communication. However, they are operated by voluntary movement, preventing use by people with the most severe impairments, such as advanced amyotrophic lateral sclerosis or severe cerebral palsy. The long-term goal is to create BCI access to all the functions of an existing commercial AAC system to provide high-efficiency functional communication to people whose physical impairments make BCI the most effective means of interacting or communicating with the world. Such a system would allow an individual with a degenerative disease to start using AAC software on a tablet with touch-screen access and maintain access to that communication software as their condition progresses to the point where they need BCI access. The overall objective of this Phase I application is to create and evaluate a prototype of BCI access to the extensive language application and communication system product line of the Prentke Romich Company (PRC). The central hypothesis is that BCIs can provide effective access to the various advanced language applications of the PRC product line that currently are used by AAC speakers. Studies with experienced users of AAC technology will test the central hypothesis and meet the objective of the application through the following specific aims: 1. Develop an AAC-BCI prototype of BCI access to the diverse commercial state-of-the-art AAC language applications on the PRC communication systems that provide high-efficiency communication. 2. Evaluate the effectiveness of the AAC-BCI prototype with experienced AAC speakers to establish the compatibility of BCI access with the complexities of the high-efficiency language applications used in PRC communication interfaces. Identify user interfaces needing Phase II development for compatibility. 3. Determine the compatibility of existing AAC service delivery, technical support, and funding mechanisms with AAC-BCI systems through surveys of prototype test subjects, potential BCI users and caregivers, and through focus groups of clinicians and assistive technology professionals. Identify support structures or product features needing Phase II development to expand AAC user populations through BCI access. This work will create a BCI input accessory for PRC's line of AAC devices. The innovation of this work is merging BCI access with the high-efficiency language production from PRC's AAC user interface designs that are matched to each person' abilities, needs, and preferences. The significance of this work is the extension of quality-of-life communication benefits to those with the most severe physical impairments, providing an AAC- BCI through an established company with a clinical support network to provide services across the lifespan.